1. Field of the Invention
The present invention relates to a method of manufacturing an exhaust gas purifying filter capable of capturing particulates such as fine carbon particles contained in an exhaust gas emitted from an internal combustion engine and purifies the captured particulates.
2. Description of the Related Art
As shown in FIG. 14, an exhaust gas purifying filter 9 of a related art has been well known. The exhaust gas purifying filter 9 captures and purifies particulates such as fine carbon particles contained in an exhaust gas 8 emitted from an internal combustion engine such as a diesel engine.
On purifying the exhaust gas 8 emitted from the internal combustion engine, the exhaust gas 8 is introduced through each opening 91 of a large size in plural cells 93 at one end surface 900 of the exhaust gas purifying filter 9. The exhaust gas 8 introduced in one cell 93 then passes through partition walls 94 formed between one cell and the adjacent cell 93 and is emitted to the outside through the openings 91 of a large size of the adjacent cell 93 formed on the other end surface of the exhaust gas purifying filter 9
As shown in FIG. 15A to FIG. 15C, a manufacturing method of the related art has been proposed by the Japanese patent laid open publication NO. 2004-42440. The manufacturing method of the related art deforms the partition wall 94 of each cell 93 by using a taper jig in order to form the opening 91 of a large size (as a large opening 91).
First, an extrusion molding of ceramic raw materials including organic binders is performed in order to form a ceramic mold body. Then, the ceramic mold body is dried and then cut into a plurality of honeycomb structure mold bodies 90. As shown in FIG. 15C, each honeycomb structure mold body 90 has a plurality of the cells 93 formed between partition walls 94. Each cell 93 penetrates the honeycomb structure body 90 in its longitudinal direction. That is, the one end of each cell 93 in the honeycomb structure mold body 90 has the opening 910. The openings 910 are formed in a honeycomb structure on each end surface 900 of the honeycomb mold body 90.
Following the above steps, as shown in FIG. 15A and FIG. 15B, a taper jig 7 is inserted in the direction W into the opening 910 of each cell 93 in the honeycomb structure body 90. The openings 910 are thereby deformed by the pressure stress applied by the taper jig 7 while the partition walls 94 are heated in order to soften them. As a result, the opening 91 of a large size (as a large opening) is formed by enlarging the area of the opening 910 of each cell 93 and the opening 92 of a small size (as a small opening) is also formed by closing the opening 910 of each adjacent cell, as shown in FIG. 15C.
Finally, a seal member 920 (see FIG. 14) is formed at the small opening 92. Thereby, the manufacturing process of forming the honeycomb structure body 9 is completed.
Because the exhaust gas purifying filter 9 has a large opening 91 of a large size, it is possible to adequately keep the area of the opening of the cell 93 that is required for introducing and purifying the exhaust gas, even if the particulate involved in the exhaust gas is accumulated on the opening on the end surface 900 of the exhaust gas purifying filter 9.
Furthermore, because the total area of the partition walls 94, that acts as a filter through which the exhaust gas passes, can be increased by decreasing the size of the openings 92 in which the plug member 920 is embedded or sealed, it is possible to increase the efficiency of the honeycomb filter for purifying the exhaust gas.
However, because the taper jig 7 of the related art has only a front end part 70, and it is necessary to deform the openings 910 of the cells 93 in the honeycomb structure body 90 by the taper jig 7 every opening 910, it is necessary to perform many manufacturing steps in order to deform all of the openings 910 of the cells 93, so that it needs much time to manufacture the exhaust gas purifying filter 9. Thus, the related art increases the total manufacturing cost for the exhaust gas purifying filter 9.